1. Field of the Invention
The present invention relates to a method for calculating an amount and determining a position of an eccentric mass existing in a rotary head apparatus of a fixed shaft type, and to an apparatus for calculating and determining the same.
2. Description of the Prior Art
Every revolving body has an eccentric mass, and this eccentric mass generates a rotational vibration. A head apparatus which is installed in a video cassette recorder (VCR) reproduces an information which is recorded on a tape or records some information on a tape while rotating. Since the head apparatus which is installed in the VCR also is a revolving body, it has an eccentric mass generates a rotational vibration. The rotational vibration of the head apparatus of the VCR is an important factor which deteriorates the quality of the reproducing image or the recording image of the tape.
U.S. Pat. No. 5,051,852 issued to Takashi Kohno, et al. discloses a mechanism for balancing a rotary magnetic head apparatus. This will be explained with reference to the accompanied FIG. 1.
FIG. 1 is a conventional head apparatus 20 having a balancer. As illustrated in this drawing, it is assumed that an unbalancer 22 having a mass of W1 is disposed on a certain portion of a rotary cylinder 21. A pair of balancers 23 are attached on the other portion of rotary cylinder 21, where the unbalancer 22 is disposed. At this time, the pair of balancers 23a and 23b are attached so as to keep symmetry with respect to an extended line A--A which is obtained by connecting unbalancer 22 and the center (O) of rotary cylinder 21 in order to maintain a balance. Also, the apparatus of Takashi Kohno includes a correcting plates which are respectively installed on the upper and lower portions of the rotary cylinder, and a motor rotor. The balancers are attached on the correcting plates according to the same method described above for balancing.
However, in the mechanism for balancing the rotary magnetic head apparatus of Takashi Kohno, et al., the problem exists that the amount of the eccentric mass of the head apparatus, and the position of the eccentric mass of the head apparatus are not disclosed.